That would explain why James Bond seemed to be a title more than an identity.

I've often fussed about who calls Q 'Q'. I usually don't have Sherlock do it due to sheer obstinacy, but I don't know whether it would be safer to make, say, a police officer aware that you're just 'Q' (and thus reveal a confidential identity) or give your real name and potentially put yourself or family in danger. I suppose a false name would come in handy there.

Q's identity card just has 'Q' on it, so obviously no one bothers with names at the office.